The Late Cenozoic crustal shortening in the north‐east margin of the Qilian Shan: Evidence from the Fengle Basin, Gansu Province

Abstract

The northeast margin of the Qilian Shan forms the front of the northeastward expansion of the Tibetan Plateau. Its Cenozoic crustal shortening is significant for understanding the uplift and growth of the Tibetan Plateau. The Fengle Basin, in the northeast margin of the Qilian Shan, is characteristic of the typical regional superimposed deformation in Cenozoic strata, documenting the Cenozoic tectonic evolution process in the northeast margin of the Tibetan Plateau. In this study, we conducted large-scale geological mapping and regional structural analysis in the Fengle Basin, and rebuilt the two phases of Late Cenozoic crustal shortening deformation in this area: (a) The NW-SE shortening deformation in the Middle-Late Miocene led to the formation of NE-striking folds in the Fengle Basin, and a hiatus between the Lower and Upper formations of the Gansu Group, probably linked with the far-field effect of the northwestward subduction of the Pacific Plate. (b) The NE-SW shortening in the Late Miocene-Early Pleistocene overprinted the early NE-striking folds, resulting in the development of a large-scale dome structure in this area. The NE-SW shortening is associated mainly with the northeastward growth of the Tibetan Plateau. This study provides crucial evidence for the reconstruction of the intracontinental deformation process in the northeastern periphery of the Tibetan Plateau.

The Late Cenozoic crustal deformation in the northeastern periphery of the Qaidam Basin, northwest China

“…Regional stratigraphic correlation reveals that the Youshashan Formation in the northeast margin of the Qaidam Basin corresponds with the Fengle Formation in Wuwei Basin on the northeast margin of Qilian Mountains (Zhao et al, 2021), as well as with the Zhangenbu Formation in the eastern part of Tibet Plateau's northeast margin (Liu, Hu, et al, 2019). Previous research has indicated that during its deposition, even the Fengle Formation in Wuwei Basin experienced NW–SE tectonic extension (Zhao et al, 2020). Similarly, when deposited, the Zhangenbu Formation was also influenced by NW–SE tectonic extension (Huang et al, 2013; Liu, 2013; Liu et al, 2020; Shi, Dong, Liu, et al, 2015).…”

Active tectonics and palaeo‐environmental change in West China ‐ Preface

“…Zhao et al (2020) conducted 1:50,000 geological mapping in the Fengle Basin, Gansu Province, and proposed Late Cenozoic crustal shortening in the northeast margin of the Qilianshan Mountain, where is located the front of the northeastward propagation of the Tibetan Plateau. Their large‐scale geological mapping in the Fengle Basin suggests a two‐phase crustal shortening in the Late Cenozoic.…”